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Underway Geophysics Lab

Dan Marone

Summary

     Expedition 384 began with a ~5 day transit from Kristiansand, Norway to the first site U1554 (REYK-6A). Due to the shallow water depth in the North Sea the bathy was not run until the ship passed through the Fair Isle channel into the Atlantic. The transit also took the ship almost entirely within EEZ boundaries of various countries which caused us not to be able to tow the magnetometer. Upon approaching the first site when the bathy was ramped up to obtain an accurate PDR it was apparent that it was not functioning correctly. Much troubleshooting was conducted throughout the expedition and can be found in more detail below. As of now now the bathy is able to be used to obtain depths when needed, but is not in full working order. The next site U1555 (REYK-13A) was a very short distance away, just far enough to lift up the thrusters for the transit. Upon the end of drilling operations the magnetometer was able to be towed for a short period before entering EEZ waters for the remainder of the transit back to Kristiandsand.

Instrumentation

Navigation

  • Winfrog navigation program was used running on the WinFrog1 PC to collect and distribute instrument data with no issues.
  • JRData Server was used to plot waypoints and the ship's track onto Google Earth with no issues.
  • Site Fix was used to collect data of the ships position over each hole during drilling/coring operations. Reports for the Ops Superintendent were printed from site fix to record the location of each hole.
  • Troubleshooting of the mysterious Trimble connection issue continued. For most of the expedition only the forward trimble was consistently connected to Winfrog. With that trimble and the gyro we were able to record accurate nav data.
  • When looking at the Trimble unit settings in a web browser using the IP address of the problem unit I noticed at one point that the I/O port configuration setting had gotten reset. These were changed to match the working unit but was ultimately not the fix to the issue. A small bit about checking the unit settings was added to the WF user guide.
  • Later on when asking Mike Cannon about the ability to install new firmware onto the Trimble unit it was noticed that some of the values in the Network→Ethernet Configuration menu of the unit were not set correctly. This is something that must have gone overlooked and was a great catch. At first it seemed like the connection was still being dropped. After resetting it a few times it became stable for the last week of the expedition. I will wait for further testing to say whether this was the fix to the issue but will keep fingers crossed that the problem has gone away.

Bathymetry   

  • No issues recording data or communicating with WinFrog.
  • Run with no issues at power levels below -6 dB. When output power levels are increased to -6 or 0 dB the signal becomes extremely faint and erratic or lost altogether.
  • Much testing and troubleshooting was conducted on the bathy hardware, and the cables going from UW to the Fwd Thyrig room junction box and onto sonar dome.
  • SyQwest was most unhelpful during all attempts to communicate with them and obtain any guidance for troubleshooting. Their response was for us to either send all of the hardware, cabling, and transducers in to their facility for testing or to buy a whole new system. 

Syqwest Hardware / Sonar Dome Troubleshooting

  • Chirp coming from the amplifier unit in UW sounds as loud as usual and scales with the power setting properly. 
  • Cables from the unit in UW to junction box in Fwd Thyrig room tested for continuity and passed. Megger test was also completed and passed on each cable.
  • When testing the cables from the junction box down to the transducers the tests failed indicating that there was an issue and possible short. The values for these tests as conducted by the SIEM ETs can be found below. As shown the 12KHz cable tested better than the 3.5KHz cable.
  • These cables were tested again after opening up the floor and top hatch. Tests were conducted from the dry side of the O'brien connections up to the junction box with the same poor results.

  • LPA-10kV A Power Module was removed, cleaned, and re-seated with no improvement. The spare module was also cleaned and tested with seemingly no difference. The original module we have been using was replaced back into the unit.
  • The cover of the lower unit was removed to inspect the internals. Everything was clean and dust free.
  • In the upper unit, the 'brains' of the Bathy, boards A00107 S/N 6209 and A00108 S/N 6210 were taken out, cleaned and inspected for any damage. The spare boards S/N 5921 and S/N 5920 were installed for testing. Upon installation when the software was turned on it would immediately show 'Sensor State Unknown'. It is unclear whether these boards are not functional or if they simply need a firmware upgrade/downgrade in order to work with our system. The process for updating firmware on the boards is described in the EXP. 350 tech report found here 

Magnetometer

  • Cable was taken from underway and spooled back onto the winch.
  • The depth is still not being recorded properly but it was decided that we did not have the expertise on board to fix the internal electronics even if we opened it up and identified the problem.
  • One short deployment was conducted during the transit back to Kristiansand. No issues running the instrument and collecting data besides the depth displaying as 0. 

Fantail

  • Level wind motor was not replaced. The screw shaft was stuck at the limit of its inboard travel. We were able to free it by removing the chain from the gears and manually turning the screw shaft gear with a large wrench. After this it worked as normal.
  • One small issue was the control of the level wind movement by the cable using the magnet on top. It would not follow the cable properly and more times than not the person using the manual button box controls would have to fight against it in order to spool the cable up cleanly. The quick solution to this was to lock the bars and magnet in place using the limit screws on either side of the bars above the level wind. This seemed like a good idea I had at the time but in reality it is very difficult to lock the control into true neutral. At least it does not fight to control it as much now, and can easily be undone if needed.
  • G gun parallel cluster was setup and deployed. Guns were cleaned and serviced after use.

  • More pictures of the G gun setup can be found in _IODP OFFICIAL\UW\UW User Guides and Info\8.Photos\GGun 384.
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